Hi,
Please check the below note. It looks to be a network issue. have you raised a message with sap to register your router.
Note 1512705 - Work process hangs during RFC communication
Workaround:
This error only happens when the network connection to the target host is unstable. Working in a stable network environment will eliminate this issue.
Why did you install an old version of saprouter. you could have insatalled saprouter 7.20.
Thanks
Rishi Abrol